If it were me, I'd avoid the active buffers since there is no need for them when going from higher to lower voltage swings. The output of a buffer/inverter is guaranteed to be at least a little less clean than what you started with.
First, check to see if the "5V" output really is a 5V signal. If it's TTL, it might swing only to about 3.5V anyway. (Connecting a weak load to ground can make this more pronounced.) Check to see if your 3.3V part's input tolerates 5V signals. The chances may be small, but it might just be that you can go direct with absolutely nothing in between. You could use a resistive divider at the destination device that serves two purposes: both attenuating the signal, and terminating it. In which case it's a win-win. If need be, the resistive divider can add a small DC offset, say if you need to drive 1.8V logic and the OCXO's Vol isn't low enough. Instead of a resistive divider, you might use a schottky switching diode to limit the positive swing. Then you get close to a replica of the OCXO's signal through the switching range of the input pin, with attenuation kicking in only when the voltage starts going too high. I don't know if these devices are still popular, but there are passive FET signal 'limiters' that work in a similar way; the signal passes through unchanged until the instantaneous voltage reaches 3V or so, and then the FET eases off and doesn't pass higher voltages. Some years ago they were popular for making 5V/3.3V signal transitions. They are supposed to have negligible delay (well, you know) when the FET is "on", they are bidirectional (not that it matters to you here), and they consume no power. I think the name "Quickswitch" was one of the brand names, and Pericom and IDT were two of the manufacturers. Regards, Andy _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.